Research will continue on the role of plasma triglycerides in atherogenesis. Several models will be studied: Alloxan diabetic rabbit, adrenal corticoid administration, detergent injections. The role of lipoprotein particle size and composition in the rate of liquid uptake and in vivo hydrolysis of fatty acid esters will be examined. We also expect to study a potential role of plasma lipid transfer activity in atherogenesis. Lipid transfer activity in rabbits is high and increases during hypercholesterolemia, whereas the rat has little or no such activity in plasma. Methods for altering the composition of plasma lipoproteins will be developed and in vivo clearance of modified lipoproteins will be compared to the original lipoprotein clearance.